Passenger-side airbag modules are normally installed behind the instrument panel of motor vehicles. (As used herein, the term "instrument panel" refers to the extended dashboard faced by the motor vehicle passenger and need not include instruments.) The module normally includes a housing for a reaction canister containing a folded airbag and means for inflating the airbag in response to a collision of sufficient severity. This module is installed behind the dashboard. The dashboard itself is provided with some type of door to permit the inflating airbag into the passenger compartment.
Since the airbag module is, of necessity, very close to the instrument panel, it presents a problem in the case of impacts or collisions below the severity required to actuate the airbag. The instrument panel is normally soft and flexible, but the airbag module is metal or a hard plastic. Accordingly, in the event of a collision less severe than that required to actuate the airbag, an occupant may be injured by impact with the housing through the instrument panel. In fact, this presents enough of a problem to result in a "Standard No. 201" by the National Highway Traffic Safety Administration of the Department of Transportation. 49 CFR chapter V, .sctn.571.201 provides, in pertinent part "Instrument panels. . . . when that area of the instrument panel that is within the head impact area is impacted . . . by a 15-pound, 6.5-inch diameter head form at a relative velocity of 12 miles per hour, the deceleration of the head form shall not exceed 80 g continuously for more than 3 milliseconds."
The reason for establishing this standard was to protect the vehicle occupant during crashes occurring below the threshold speed required to deploy the airbag system. Even at these low speeds, head injuries may occur on impact with a dashboard which is too rigid.
In the past this problem has been met by weakening the airbag housing so that it crushes under impact. An example of such an approach will be found in co-pending U.S. patent application Ser. No. 08/392,531 of Jon E. Miles, Scott L. Hansen, and John T. Jensen for COLLAPSIBLE AIRBAG CANISTER, filed Feb. 23, 1995 and assigned to the same assignee as the present invention. While such an approach has been successful, it is often desirable to have a rigid airbag housing to insure that the airbag is restrained and deploys correctly.
Accordingly, it is a primary object of the present invention to provide an energy absorbing zone which is separate from the airbag housing. Other objects, features, and advantages will become apparent from the following description and appended claims.